Geostationary Operational Environmental Satellite-16(GOES-16) Advanced Baseline Imager(ABI) observations of brightness temperature(TB) are used to examine the temporal evolutions of convection-affected structures of H...Geostationary Operational Environmental Satellite-16(GOES-16) Advanced Baseline Imager(ABI) observations of brightness temperature(TB) are used to examine the temporal evolutions of convection-affected structures of Hurricane Irma(2017) during its rapid intensification(RI) period from 0600 to 1800 UTC 4 September 2017.The ABI observations reveal that both an elliptical eye and a spiral rainband that originated from Irma's eyewall obviously exhibit wavenumber-2 TB asymmetries.The elliptical eye underwent a counterclockwise rotation at a mean speed of a wavenumber-2 vortex Rossby edge wave from 0815 to 1005 UTC 4 September.In the following about 2 hours(1025–1255 UTC 4 September),an inner spiral rainband originated from the eyewall and propagated at a phase speed that approximates the vortex Rossby wave(VRW) phase speed calculated from the aircraft reconnaissance data.During the RI period of Irma,ABI TB observations show an on–off occurrence of low TB intrusions into the eye,accompanying a phase lock of eyewall TB asymmetries of wavenumbers 1 and 2 and an outward propagation of VRW-like inner spiral rainbands from the eyewall.The phase lock leads to an energy growth of Irma's eyewall asymmetries.Although the eye remained clear from 1415 to 1725 UTC 4 September,an inner spiral rainband that originated from a large convective area also had a VRW-like outward propagation,which is probably due to a vertical tilt of Irma.This study suggests a potential link between convection sensitive GOES imager observations and hurricane dynamics.展开更多
An f-plane quasi-geostrophic barotropic vorticity equation model of high resolution is designed in this paper in order to investigate the characters of vorticity propagation and the effect of nonlinearity on the propa...An f-plane quasi-geostrophic barotropic vorticity equation model of high resolution is designed in this paper in order to investigate the characters of vorticity propagation and the effect of nonlinearity on the propagation within a typhoon circulation,wherein two mesoscale vortices coexist at different radial positions.The results of 10 sets of experiments suggest that in comparison with only one vortex,the intensity of the inward propagations of vorticity strengthens distinctly,vorticity detains in the inner region of typhoon circulation for a longer time,and the local maximum wind speed in the inner region increases clearly.The introduction of nonlinear advection into the model weakens the intensity of both inward and outward propagations of vorticity,but makes the inward propagation up to a position closer to the center of typhoon.展开更多
基金Supported by the National Key Research and Development Program of China (2018YFC1507004)。
文摘Geostationary Operational Environmental Satellite-16(GOES-16) Advanced Baseline Imager(ABI) observations of brightness temperature(TB) are used to examine the temporal evolutions of convection-affected structures of Hurricane Irma(2017) during its rapid intensification(RI) period from 0600 to 1800 UTC 4 September 2017.The ABI observations reveal that both an elliptical eye and a spiral rainband that originated from Irma's eyewall obviously exhibit wavenumber-2 TB asymmetries.The elliptical eye underwent a counterclockwise rotation at a mean speed of a wavenumber-2 vortex Rossby edge wave from 0815 to 1005 UTC 4 September.In the following about 2 hours(1025–1255 UTC 4 September),an inner spiral rainband originated from the eyewall and propagated at a phase speed that approximates the vortex Rossby wave(VRW) phase speed calculated from the aircraft reconnaissance data.During the RI period of Irma,ABI TB observations show an on–off occurrence of low TB intrusions into the eye,accompanying a phase lock of eyewall TB asymmetries of wavenumbers 1 and 2 and an outward propagation of VRW-like inner spiral rainbands from the eyewall.The phase lock leads to an energy growth of Irma's eyewall asymmetries.Although the eye remained clear from 1415 to 1725 UTC 4 September,an inner spiral rainband that originated from a large convective area also had a VRW-like outward propagation,which is probably due to a vertical tilt of Irma.This study suggests a potential link between convection sensitive GOES imager observations and hurricane dynamics.
基金the special project of the Ministry of Science and Technology of China under grant No.2001DIA20026the National Natural Science Foundation of China under grant No.49975013
文摘An f-plane quasi-geostrophic barotropic vorticity equation model of high resolution is designed in this paper in order to investigate the characters of vorticity propagation and the effect of nonlinearity on the propagation within a typhoon circulation,wherein two mesoscale vortices coexist at different radial positions.The results of 10 sets of experiments suggest that in comparison with only one vortex,the intensity of the inward propagations of vorticity strengthens distinctly,vorticity detains in the inner region of typhoon circulation for a longer time,and the local maximum wind speed in the inner region increases clearly.The introduction of nonlinear advection into the model weakens the intensity of both inward and outward propagations of vorticity,but makes the inward propagation up to a position closer to the center of typhoon.
